Editing Guyot (section)

==Formation==
Guyots show evidence of having once been above the surface, with gradual [[subsidence]] through stages from fringed [[reef]]ed mountain, [[coral]] [[atoll]], and finally a flat-topped submerged mountain.<ref name="EBchecked" /> Seamounts are made by extrusion of lavas piped upward in stages from sources within the Earth's mantle, usually [[Hotspot (geology)|hotspots]], to vents on the seafloor.  The volcanism invariably ceases after a time, and other processes dominate.  When an undersea volcano grows high enough to be near or breach the ocean surface, wave action or coral reef growth tend to create a flat-topped edifice.  However, all ocean crust and guyots form from hot magma or rock, which cools over time.  As the lithosphere that the future guyot rides on slowly cools, it becomes denser and sinks lower into Earth's mantle, through the process of [[isostasy]].  In addition, the erosive effects of waves and currents are found mostly near the surface: the tops of guyots generally lie below this higher-erosion zone.

This is the same process that gives rise to higher seafloor topography at oceanic ridges, such as the [[Mid-Atlantic Ridge]] in the Atlantic Ocean, and deeper ocean at [[abyssal plain]]s and [[oceanic trench]]es, such as the [[Mariana Trench]]. Thus, the island or shoal that will eventually become a guyot slowly [[Subsidence|subsides]] over millions of years.  In the right climatic regions, coral growth can sometimes keep pace with the subsidence, resulting in coral atoll formation, but eventually the corals dip too deep to grow and the island becomes a guyot.  The greater the amount of time that passes, the deeper the guyots become.<ref name="P7qOd">{{cite web|url=http://www.utdallas.edu/~pujana/oceans/guyot.html|title=Guyot|website=www.utdallas.edu|access-date=15 January 2019}}</ref>

Seamounts provide data on movements of tectonic plates on which they ride, and on the [[rheology]] of the underlying [[lithosphere]]. The trend of a seamount chain traces the direction of motion of the lithospheric plate over a more or less fixed heat source in the underlying [[asthenosphere]], the part of the Earth's mantle beneath the lithosphere.<ref name="IvUIG">Seamounts are made by extrusion of lavas piped upward in stages from sources within the Earth's mantle to vents on the seafloor. Seamounts provide data on movements of tectonic plates on which they ride, and on the rheology of the underlying lithosphere. The trend of a seamount chain traces the direction of motion of the lithospheric plate over a more or less fixed heat source in the underlying asthenosphere part of the Earth's mantle.</ref> There are thought to be up to an estimated 50,000 seamounts in the Pacific basin.<ref name="SeamountCount">{{cite journal | title=Pacific seamount volcanism in space and time | author=Hillier, J. K. | journal=Geophysical Journal International | year=2007 | volume=168 | issue=2 | pages=877–889 | doi=10.1111/j.1365-246X.2006.03250.x| bibcode=2007GeoJI.168..877H | doi-access=free| url=https://repository.lboro.ac.uk/articles/journal_contribution/Pacific_seamount_volcanism_in_space_and_time/9481115/1/files/17106296.pdf }}</ref> The [[Hawaiian–Emperor seamount chain]] is an excellent example of an entire volcanic chain undergoing this process, from active volcanism, to coral reef growth, to atoll formation, to subsidence of the islands and becoming guyots.